Biomedical subjects

Robin E Everts

Publications and source records attributed to Robin E Everts.

7 recordsLinked to original sources

PubMed2006

Plane of nutrition prepartum alters hepatic gene expression and function in dairy cows as assessed by longitudinal transcript and metabolic profiling.

Liver metabolism and health in dairy cows during the periparturient period are affected by plane of nutrition prepartum. Long-term adaptations in hepatic gene expression are important for complete understanding of liver function. We examined temporal gene expression profiles during the dry period and early lactation in liver of Holstein cows fed moderate dietary energy ad libitum or restricted during the entire dry period using a microarray consisting of 7,872 annotated cattle cDNA inserts and quantitative RT-PCR. We identified 85 genes with expression patterns that were affected by level of energy intake prepartum over time. Restricted energy intake prepartum resulted in more pronounced upregulation of genes with key functions in hepatic fatty acid oxidation (CPT1A, ADIPOR2), gluconeogenesis (PC), and cholesterol synthesis (SC4MOL). Ad libitum feeding upregulated a number of genes associated with liver triacylglycerol synthesis (DGAT1) and proinflammatory cytokines (TNFAIP3). Genomic responses to ad libitum feeding were accompanied by increased incorporation of palmitate to esterified products in vitro and increased liver triacylglycerol concentration in vivo. Overall, gene expression profiles due to plane of nutrition prepartum partly explained differences in rates of liver palmitate metabolism, blood serum metabolite concentrations, and liver tissue triacylglycerol concentration. Our data show that moderate overfeeding of energy in the dry period, in the absence of obesity, results in transcriptional changes predisposing cows to fatty liver and perhaps compromising overall liver health during the periparturient period. In this context, controlled energy intake may confer an advantage to the cow by triggering hepatic molecular adaptations well ahead of parturition.

Animals↗

PubMed2006

Discovery of eight novel divergent homologs expressed in cattle placenta.

Ten divergent homologs were identified using a subtractive bioinformatic analysis of 12,614 cattle placenta expressed sequence tags followed by comparative, evolutionary, and gene expression studies. Among the 10 divergent homologs, 8 have not been identified previously. These were named as follows: cattle cerebrum and skeletal muscle-specific transcript 1 (CSSMST1), cattle intestine-specific transcript 1 (CIST1), hepatitis A virus cellular receptor 1 amino-terminal domain-containing protein (HAVCRNDP), prolactin-related proteins 8, 9, and 11 (PRP8, PRP9, and PRP11, respectively) and secreted and transmembrane protein 1A and 1B (SECTM1A and SECTM1B, respectively). In addition, two previously known divergent genes were identified, trophoblast Kunitz domain protein 1 (TKDP1) and a new splice variant of TKDP4. Nucleotide substitution analysis provided evidence for positive selection in members of the PRP gene family, SECTM1A and SECTM1B. Gene expression profiles, motif predictions, and annotations of homologous sequences indicate immunological and reproductive functions of the divergent homologs. The genes identified in this study are thus of evolutionary and physiological importance and may have a role in placental adaptations.

Amino Acid Sequence↗

PubMed2005

Global gene expression profiles reveal significant nuclear reprogramming by the blastocyst stage after cloning.

Nuclear transfer (NT) has potential applications in agriculture and biomedicine, but the technology is hindered by low efficiency. Global gene expression analysis of clones is important for the comprehensive study of nuclear reprogramming. Here, we compared global gene expression profiles of individual bovine NT blastocysts with their somatic donor cells and fertilized control embryos using cDNA microarray technology. The NT embryos' gene expression profiles were drastically different from those of their donor cells and closely resembled those of the naturally fertilized embryos. Our findings demonstrate that the NT embryos have undergone significant nuclear reprogramming by the blastocyst stage; however, problems may occur during redifferentiation for tissue genesis and organogenesis, and small reprogramming errors may be magnified downstream in development.

Animals↗

PubMed2005

Temporal gene expression profiling of liver from periparturient dairy cows reveals complex adaptive mechanisms in hepatic function.

Long-term molecular adaptations in liver from high-producing dairy cows are virtually unknown. Liver from five Holstein cows was biopsied at -65, -30, -14, +1, +14, +28, and +49 days relative to parturition for transcript profiling using a microarray consisting of 7,872 annotated cattle cDNA inserts. More than 5,000 cDNA elements represented on the microarray were expressed in liver. From this set we identified 62 differentially expressed genes related to physiological state, with a false discovery rate threshold of P = 0.20. The dominant expression pattern consisted of upregulation from day -30 through day +1, followed by downregulation through day +28. There was a threefold decrease from day -65 through day +14 in expression of IGFBP3, GSTM5, and PDPK1. These genes mediate IGF-I transport, oxidative stress, and glucose homeostasis, respectively. IGFBP3, EIF4B, and GSTM5 mRNA levels were positively correlated with blood serum total protein. Correlation analysis showed positive associations between serum nonesterified fatty acids and mRNA expression for SAA1, CPT1A, ACADVL, and TFAP2A. Transcript levels of ACSL1, PPARA, and TFAP2A were positively correlated with serum beta-hydroxybutyrate. Expression patterns for certain genes (e.g., IGFBP3, HNF4A, GPAM) revealed adaptations commencing well ahead of parturition, suggesting they are regulated by factors other than periparturient hormonal environment. Results provide evidence that hepatic inflammatory responses occurring near parturition initiate or augment adipose catabolism. In this context, cytokines, acute-phase proteins, and serum nonesterified fatty acids are key players in periparturient cow metabolism. We propose a model for integrating gene expression, metabolite, and liver composition data to explain physiological events in placenta, adipose, and liver during the periparturient period.

Adaptation, Physiological↗

PubMed2005

A 7872 cDNA microarray and its use in bovine functional genomics.

The strategy used to create and annotate a 7872 cDNA microarray from cattle placenta and spleen cDNA sequences is described. This microarray contains approximately 6300 unique genes, as determined by BLASTN and TBLASTX similarity search against the human and mouse UniGene and draft human genome sequence databases (build 34). Sequences on the array were annotated with gene ontology (GO) terms, thereby facilitating data analysis and interpretation. A total of 3244 genes were annotated with GO terms. The array is rich in sequences encoding transcription factors, signal transducers and cell cycle regulators. Current research being conducted with this array is described, and an overview of planned improvements in our microarray platform for cattle functional genomics is presented.

Animals↗

PubMed2004

A 1463 gene cattle-human comparative map with anchor points defined by human genome sequence coordinates.

A second-generation 5000 rad radiation hybrid (RH) map of the cattle genome was constructed primarily using cattle ESTs that were targeted to gaps in the existing cattle-human comparative map, as well as to sparsely populated map intervals. A total of 870 targeted markers were added, bringing the number of markers mapped on the RH(5000) panel to 1913. Of these, 1463 have significant BLASTN hits (E < e(-5)) against the human genome sequence. A cattle-human comparative map was created using human genome sequence coordinates of the paired orthologs. One-hundred and ninety-five conserved segments (defined by two or more genes) were identified between the cattle and human genomes, of which 31 are newly discovered and 34 were extended singletons on the first-generation map. The new map represents an improvement of 20% genome-wide comparative coverage compared with the first-generation map. Analysis of gene content within human genome regions where there are gaps in the comparative map revealed gaps with both significantly greater and significantly lower gene content. The new, more detailed cattle-human comparative map provides an improved resource for the analysis of mammalian chromosome evolution, the identification of candidate genes for economically important traits, and for proper alignment of sequence contigs on cattle chromosomes.

Animals↗

PubMed2002

A 3800 gene microarray for cattle functional genomics: comparison of gene expression in spleen, placenta, and brain.

A cDNA microarray representing approximately 3800 cattle genes was created for functional genomic studies. The array elements were selected from > 7000 cDNA clones identified in a large-scale expressed sequence tag (EST) project that utilized spleen and normalized and subtracted placenta cDNA libraries. Sequence similarity searches of the 3820 ESTs represented on the array using BLASTN identified 3290 (86.1%) as putative human orthologs, with the remainder consisting of "novel" genes or highly divergent orthologs. Experiments were conducted with a prototype 768 gene microarray created from spleen cDNAs and with the 3800 gene array that included genes from spleen and placenta. The 768 gene array was used to profile RNA transcripts expressed by adult and fetal spleen. The 3800 gene array was used to profile transcripts expressed by adult brain and placenta. Microarray analysis of RNA extracted from fetal and adult spleen identified 29 genes that were differentially expressed two-fold or more. Transcriptional differences of two of these genes, IGJ and CTSS, were confirmed using TaqMan technology. The comparison of brain and placenta revealed 400 genes expressed at higher levels in brain and 72 genes expressed at higher levels in placenta. These results demonstrate the potential power of microarrays for understanding the molecular mechanisms of cattle development, disease resistance, nutrition, fertility and production traits.

Animals↗